1. Field of the Invention
The present invention relates to an electric rotary shaver and more particularly to a structure that tiltably supports outer cutters in a cutter frame of an electric rotary shaver.
2. Prior Art
FIG. 9 is a perspective view of the overall structure of a conventional electric rotary shaver. In this electric shaver 10, a cutter head 20 is detachably mounted on the upper portion of a main body case 12. Three outer cutters 22 are mounted in the cutter head 20 so that the centers of the outer cutters are arranged at the vertices of an equilateral triangle. Slits for introducing hair are formed in the radial direction in the outer cutters 22. In each outer cutter 22, an annular outside hair introduction region V and inside hair introduction region W are formed in a concentric configuration, and a groove is formed in the boundary area between the outside hair introduction region V and inside hair introduction region W.
FIG. 10 shows the internal structure of the above electric rotary shaver. The cutter head 20 is constructed from a cutter frame 30, metal outer cutters 22, outer cutter holders 24 that hold the outer cutters 22, metal inner cutters 26, inner cutter bases 28 that support the inner cutters 26, and cutter retaining plates 31 that hold the inner cutters 26 so that the inner cutters 26 are rotated. The cutter frame 30, outer cutter holders 24, inner cutter bases 28 and cutter retaining plates 31 are all made of a synthetic resin. The outer cutters 22 are supported so that they cannot rotate relative to the outer cutter holders 24, thus ensuring the outer cutters 22 not to rotate together with the inner cutters 26.
The reference numeral 32 is a cutter cradle that is installed so as to cover the opening of the main body case 12. Inner cutter drive shafts 34 that transmit the rotational driving force of a motor 50 to the inner cutters 26 protrude from the cutter cradle 32 in the installation positions of the respective inner cutters 26. The inner cutter drive shafts 34 are provided in coaxial with the inner cutter bases 28 and engage with the inner cutter bases 28 in a dovetail engagement so that each of the inner cutter drive shafts 34 can rotate as a unit with the corresponding inner cutter base 28.
The reference numeral 36 refers to springs that constantly urge the inner cutter drive shafts 34 upward. The outer cutters 22 are supported floatingly by these springs 36 via the inner cutters 26, inner cutter bases 28 and inner cutter drive shafts 34.
Engaging projections 38 are disposed on the outer circumferences of the lower ends of the inner cutter drive shafts 34 and engaged with a plurality of shaft engaging portions 42 disposed in upright positions on the inner cutter drive gears 40, and the inner cutter drive gears 40 are engaged with a gear 52 fastened to the output shaft of the motor 50. The inner cutter drive shafts 34 are thus linked to the motor 50. The inner cutter drive shafts 34 are provided so as to tilt in all directions with respect to the axial lines of the inner cutter drive gears 40.
As described above, the outer cutters 22 are supported while being urged by the springs 36 in a direction that causes the outer cutters 22 to protrude to the outside. The outer cutters 22 are thus movable in and out of the outer cutter holders 24, and also the outer cutters 22 are tiltable within a specified angular range in all directions inside the outer cutter holders 24. As shown in FIG. 10, the outer cutters 22 are disposed in the outer cutter holes 44. However, since the internal diameter of the outer cutter holes 44 is slightly larger than the external diameter of the outer cutters 22, the outer cutters 22 can move inward and outward with respect to the outer cutter holders 44 and can tilt within a specified angular range in any desired direction.
As seen from the above, the outer cutters 22 are supported in the cutter frame 30 so that the outer cutters 22 can tilt and move inward and outward. The outer cutters 22 are, therefore, fitted against the skin as a result of the outer cutters 22 protruding outward to an appropriate degree and tilting in the desired direction when the electric shaver is brought into contact with the jaw, cheek, etc., so that hair is cut reliably.
In a conventional electric shaver, the outer cutters 22 can tilt with respect to the cutter frame 30 because the internal diameter of the outer cutter holes 44 is slightly larger than the external diameter of the outer cutters 22 (as described above). The outer cutters 22 are tiltable because of this clearance.
However, in the conventional electric shaver, the clearance between the outer cutter holes 44 and outer cutters 22 is not very large. As a result, even in cases where the outer cutters 22 are allowed to tilt due to this clearance, the outer cutters 22 cannot tilt to a very great extent. If an increased clearance is given between the outer cutters 22 and the outer cutter holes 44 to an excessive extent, the outer cutters 22 are loose in the outer cutter holes 44. As a result, it becomes difficult to determine the center positions of the outer cutters 22, and the rotation of the inner cutters 26 becomes unstable.
FIGS. 11(a) and 11(b) show the manner of tilting of the outer cutters 22 of a conventional electric shaver. As seen from FIG. 11(a), the outer cutter 22 is disposed with a slight gap left between the outer cutter 22 and the outer cutter hole 44, and the outer cutter 22 tilts inside the corresponding outer cutter hole 44 as shown in FIG. 11(b). When the outer cutter 22 tilts inside the outer cutter hole 44 in a conventional electric shaver, as seen from FIG. 11(b), once the protruding edge 21 at the lower-end edge of the outer cutter 22 contacts the undersurface of the outer cutter hole 44, the outer cutter 22 cannot tilt any further from this state. Thus, the tilting angle of the outer cutters 22 is limited. As seen from the above, in a conventional electric shaver, since the tilting angle of the outer cutters 22 is restricted by the positional relationship between the outer cutters 22 and the outer cutter holes 44, it is difficult to increase the tilting range of the outer cutters 22.
The present invention solves the above-described problems. The object of the present invention is to provide an electric rotary shaver in which the outer cutters are supported so as to be movable and tiltable with respect to the cutter frame and in which the outer cutters have increased tilting range compared to that of a conventional electric shaver. Thus, in the electric rotary shaver of the present invention, fitting between the skin and the outer cutters is good, and the cutting efficiency is also good.
In order to accomplish the above object, the present invention is structured as described below.
More specifically, in an electric rotary shaver that comprises: a cutter frame provided with a plurality of outer cutter holes, outer cutters disposed in respective outer cutter holes so as to be tiltable in any direction, and inner cutters rotatably disposed inside the outer cutters, the inner cutters being connected to inner cutter drive shafts that are rotationally driven and urged in a direction that causes the inner cutter drive shafts to protrude outward; the rotary shaver is further comprised of: a cutter retaining plate provided inside the cutter frame so as to be on a main body side of the electric shaver, and fulcrum plates respectively shaft-supported in the cutter retaining plate in a tiltable fashion, the fulcrum plates being disposed so as to positionally correspond respectively to the outer cutter holes; and in addition, the outer cutters are shaft-supported in the respective fulcrum plates via supporting members in a direction that is perpendicular to a direction in which the fulcrum plates are shaft-supported by the cutter retaining plate, so that the outer cutters are tiltable.
In the present invention, the supporting directions in which the respective fulcrum plates are shaft-supported are set so as to be disposed on radial lines that passes through the center of the cutter frame, and the supporting directions in which the outer cutters are shaft-supported are set so as to be disposed in directions that are perpendicular to such radial lines.
Also, in the present invention, pairs of supporting pillars that have pivot shafts are formed on the cutter retaining plate at positions that correspond to the respective outer cutter holes, and pairs of engagement pillars that have slot-form engaging holes are formed on the fulcrum plates; and the pivot shafts are engaged with the engaging holes, thus allowing the outer cutters to be moved up and down.
Furthermore, in the present invention, outer cutter fastening rings are shaft-supported in the fulcrum plates, and the outer cutters are tiltably supported in the fulcrum plates by way of the outer cutter fastening rings.
In addition, in the present invention, the outer cutters are provided in outer cutter casings that are set tiltable inside the outer cutter holes, and the outer cutter casings are supported in the outer cutter fastening rings.
Also, in the present invention, the cutter retaining plate is constantly urged with respect to the cutter frame in a direction that causes the outer cutters to protrude outward and is installed so that the cutter retaining plate can be moved up and down.